Networking::Telecom Closet Design
Build At least One Closet Per Floor
The communications industry has established infrastructure standards that have served to foster the idea of interoperability. One of those standards establishes that the maximum cable distance between a communications closet and the wall outlet in a classroom or office should not exceed 90 meters (295 feet). In the average building this specification establishes that you should build at least one centrally located closet per floor. Larger building will require more than one closet per floor to stay within the 90-meter cable length limitation. Installing cables that exceed the 90-meter limitation will generally result in a communications network that never performs satisfactorily.
Create a Safe Working Environment
The telecommunications worker needs to be able to stand about arms length or two feet away from the equipment he is working on. This reduces the feeling of claustrophobia, and provides adequate room for stress-reduced movement. You should also consider the affect of the working space on the employee if he is standing on a ladder in the closet or squatting down low to work on equipment at the bottom of a wall or rack. In both of these cases the employee needs an additional two feet of space in front of the equipment to insure free movement. There should also be room on both sides of the equipment for several people to assist in lifting the equipment during installation or removal. These conditions exist for both the front and back of the equipment that is located in a communications rack. A good working environment for a telecommunications closets includes four feet of clear space extending out from the front of the equipment mounted on a wall and four feet out from the front and back of equipment mounted in a rack with two feet of clearance on each side.
Provide Enough Space for Today's Technology as well as the Next Generation of Technology
Your electronics and cabling infrastructure can be bolted to the wall or installed in equipment racks. Equipment racks are about 24 inches wide and up to 7 feet high. The equipment rack, when installed properly, provides the best environment for your equipment and cable infrastructure cross-connects. The average closet will require one rack for electronics and one rack for cabling infrastructure cross-connects. If your initial design fills more than half of either rack then plan for a third or fourth rack. This extra space will be used for any future expansion and will allow new technologies to be deployed without disturbing the legacy facilities. Over the past twenty years of computer networking we have seen four changes in the dominant cabling infrastructure and many more changes in niche specific cabling systems. This means that about every three to five years your technicians are making significant changes in the communications closets. If you don't allow for the installation of new technology then you are forced to remove the old technology before installing the new. This usually results in several weeks or months of disrupted service. If the closet were large enough then the new technology could be installed without interrupting service. After the new service was tested and all users move to it then the old service could be removed in preparation for the next change. You should design for twice as much equipment and cable infrastructure space as you initially need.
Cable management means providing an ordered space for the interconnecting cables between the electronic devices. Without this space the cables hang in front of the electronics and severely impede the repair process. You should plan for an additional six to eight inches of space to each side of the rack for cable management.
We have grown dependant on the telecommunication infrastructure. When our phone fails or the computer can't get to the network we expect an immediate repair. You do not want to have your technician waiting for a meeting to finish or a class to be over before they can enter the communications closet. For this reason the closet should be accessible from a major hallway. The closet should be clearly marked "Telecommunications Closet" and have unrestricted technician access. The closet should also be secured by a restricted access key system to reduce the chances of malicious "denial of service" attacks and to discourage building occupants from storing items in the closets.
Minimum Telecommunications Closet Size
From the above requirements there are two possible minimum configurations for the telecommunications closet. The first design is a 10' x 10' room with one door onto a major hallway. This design is preferred in areas supporting student classrooms. The second design is a 5' x 10' room with two sets of double doors on the 10' wall of a major hallway (the doors must swing into the hallway). The second design uses the hallway as temporary space during times of maintenance and is most practical in low traffic hallways such as office areas.
Other Considerations for Closet Design
Include space for an uninterruptible power supply in each closet. There should be a minimum of two electrical circuits in each closet. Design for good even lighting throughout the entire closet space both high and low. And finally provide for enough cooling capacity for the electronics in the room.
From: Overview of the best practices for telecommunications closet design, http://net-services.ufl.edu/infrastructure/closetdesign.html